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Öğe Exergetic and sustainability performance assessment of geothermal (ground source) ejector heat pumps(INDERSCIENCE ENTERPRISES LTD, 2012) Alsuhaibani, Zeyad; Ersoy, H. Kursad; Hepbasli, ArifAlthough ejectors have been used in cooling/refrigeration and Heat Pumps (HP) applications for a long time, utilisation of Geothermal Ejector Heat Pump (GEHP) with Ground-Heat Exchanger (GHE) is a new idea, which has recently appeared in the literature. In this study, we model a GEHP system with a GHE in terms of exergetic aspects and apply our model to this system in the heating mode. The system consists of mainly three parts, namelya GEHP unit, a GHE, and a heat distribution system. We determine the exergy transports between the components and the consumptions in each of the components of the whole system and we also calculate exergy efficiency and Sustainability Index (SI) values for the system components to evaluate its performance. In this regard, exergy efficiency values for the GEHP unit and whole system are calculated to be 85.3% and 84.6% on the product/fuel basis at dead (reference) state values for 19 degrees C and 101.325 kPa, respectively. An improvement of about 16.17% in the energetic and exergetic coefficient of performance value of the GEHP unit is obtained by adding an ejector to the HP system. SI values for some system components such as ejector, compressor, condenser and evaporator are also obtained to be 1.82, 2.79, 3.22 and 3.94, respectively.Öğe Experimental investigation on motive nozzle throat diameter for an ejector expansion refrigeration system(PERGAMON-ELSEVIER SCIENCE LTD, 2016) Sag, Nagihan Bilir; Ersoy, H. KursadIn this study, ejector was used to reduce throttling losses in a vapour compression refrigeration system. Effects on system performance of throat diameter and position of motive nozzle of ejector were investigated experimentally. An ejector was designed based on the established mathematical model and manufactured. The experiments were carried out by using different primary nozzle throat diameters. The experiments were further conducted by changing condenser water inlet temperature, which is one of the external parameters. The experimental results of the ejector system and those of the classic system were compared under same external operating conditions and for the same cooling capacity. In order to obtain same external operating conditions in both systems, the inlet conditions of the brine supplied to the evaporator and inlet water conditions (flow rate and temperature) to the condenser were kept constant. Maximum performance was obtained when the primary nozzle throat diameter was 2.3 mm within the areas considered in this study. When compared, it was experimentally determined that the ejector system that uses the optimum motive nozzle throat diameter exhibits higher COP than the classic system by 5-13%. Furthermore, it was found that the variation of coefficient of performance based on position of motive nozzle in two-phase ejector expander refrigeration cycle is lower than 1%. (C) 2016 Elsevier Ltd. All rights reserved.Öğe The influence of ejector component efficiencies on performance of Ejector Expander Refrigeration Cycle and exergy analysis(INDERSCIENCE ENTERPRISES LTD, 2010) Ersoy, H. Kursad; Bilir, NagihanIn order to identify the amounts and locations of irreversibility within the components of the cycle, exergy analysis is employed. A two-phase constant area ejector flow model was used. As the ejector component efficiencies increase, coefficient of performance and exergy efficiency increase. As a result, when the efficiencies of motive nozzle and diffuser are 100%, the efficiency of ejector suction nozzle increases from 20% to 100%, whereas the improvement ratio in cooling coefficient of performance and that of exergy efficiency increase at approximately 4.3 times. It was also found that as ejector component efficiencies fall, optimum ejector area ratio increases.Öğe Performance improvement of the vapour compression refrigeration cycle by a two-phase constant area ejector(WILEY, 2009) Bilir, Nagihan; Ersoy, H. KursadThe performance of a vapour compression system that uses an ejector as an expansion device was investigated. In the analysis, a two-phase constant area ejector flow model was used. R134a was selected as the refrigerant. According to the obtained results, for any operating temperature there are different optimum values of pressure drop in the suction chamber, ejector area ratio, ejector outlet pressure and cooling coefficient of performance (COP). As the difference between condenser and evaporator temperatures increases, the improvement ratio in COP rises whereas ejector area ratio drops. The minimum COP improvement ratio in the investigated field was 10.1%, while its maximum was 22.34%. Even in the case of an off-design operation, the performance of a system with ejector is higher than that of the basic system. Copyright (C) 2008 John Wiley & Sons, Ltd.Öğe Performance of a solar ejector cooling-system in the southern region of Turkey(ELSEVIER SCI LTD, 2007) Ersoy, H. Kursad; Yalcin, Sakir; Yapici, Rafet; Ozgoren, MuammerPerformance variations of a solar-powered ejector cooling-system (SECS) using an evacuated-tube collector are presented for Antalya, Aydin, Konya and Urfa cities located in the southern region of Turkey by means of hourly and monthly average ambient temperature and solar radiation meteorological data. A SECS, based on a constant-area ejector flow model and using R-123, was considered. The cooling season and period were taken into account for the 6 months (May-October) and the hours 8:00-17:00, respectively. It was found that the evacuated-tube collector efficiency depending upon the ambient temperature and solar radiation within the day was remarkably varied. However, for all the cities, the cooling capacities of the SECS were very similar. When generator, condenser, and evaporator temperatures were taken, namely, 85 degrees C, 30 degrees C and 12 degrees C, the maximum 2 overall coefficient of performance and the cooling capacity were obtained as 0.197 and 178.26 W/m(2) respectively, at 12:00 in August for Aydin. The evacuated-tube collector area per ton cooling was found to be around 21 m(2) at. noontime in August for all the cities. Furthermore, at the off-design conditions, a performance map of the system was derived and discussed. It was determined that the SECS could be used for office-cooling purposes during the hours (8:00-15:00) in the southern region of Turkey. (c) 2006 Elsevier Ltd. All rights reserved.Öğe Preliminary experimental results on the R134a refrigeration system using a two-phase ejector as an expander(ELSEVIER SCI LTD, 2014) Ersoy, H. Kursad; Sag, Nagihan BilirThe use of an ejector as an expansion device instead of an expansion valve for expansion work recovery in a vapor-compression cycle was experimentally investigated. The coefficient of performance (COP) values for both conventional and ejector systems were experimentally investigated under the same external conditions. It was observed that, although the drop in the refrigerant pressure in the evaporator of the ejector system was almost negligible, it rose as high as 133 kPa in the conventional system. Depending on the operating conditions, it was found that the work recovery in the ejector was between 14% and 17%. It was also found that the refrigeration system with an ejector as the expander exhibited a COP that was 6.2-14.5% higher than that of the conventional system. The experimental results were found to comply with the theoretical results within an error of approximately 10%. (C) 2014 Elsevier Ltd and IIR. All rights reserved.
